Studies on the biology of the red sea bream Chrysophrys major III. Metabolic response to starvation in different salinities

TLDR: Enhanced survival during starvation in 1/3 sea water was observed to be associated with maintenance of plasma protein and elevation of hepatic glucose-6-phosphate dehydrogenase activity, and it is suggested that sea breams be transferred to an iso-osmotic medium whenever the threat of starvation prevails.

Abstract: Red sea breams were kept at 20°C without food at 3 salinities (full sea water, 950 mOsm kg-1; 2/3 sea water, 640 mOsm kg-1; 1/3 sea water, 330 mOsm kg-1). In fish adapted to all 3 salinities, starvation resulted in marked decline of plasma FFA and β-hydroxybutyrate and liver glycogen levels but plasma glucose and lactate concentrations were maintained. These findings suggest that with the onset of starvation, enhanced hepatic glycogenolysis and decreased fat utilization occurred. Fish, adapted to full and 2/3 sea water, could not survive for more than 19 d without food. However, fish adapted to 1/3 sea water could tolerate 27 d of starvation. Enhanced survival during starvation in 1/3 sea water was observed to be associated with maintenance of plasma protein and elevation of hepatic glucose-6-phosphate dehydrogenase activity. It is suggested that sea breams be transferred to an iso-osmotic medium whenever the threat of starvation prevails, but this suggestion has yet to be evaluated in economic terms.